(a) Field of the Invention
The present invention relates to a lateral flow atomic layer deposition device.
(b) Description of the Related Art
Efforts to improve an apparatus or process for forming a high quality thin film on a substrate in the field of semiconductor devices have been made. Atomic layer deposition (ALD) has recently been proposed, in which two or more reaction materials are temporally isolated and sequentially fed onto a substrate, and a thin film is grown thereon through a surface reaction, followed by repeating such a process so as to form a thin film with a desired thickness. As the film is formed through a surface reaction, a thin film with a uniform thickness is formed over the entire surface of the substrate irrespective of protrusions and depressions thereof, and impurities are prevented from intruding into the thin film, thereby ensuring excellent film characteristics.
Various structures of reactors have been developed so as to realize the atomic layer deposition (ALD) process that is widely applied to semiconductor processes. Regarding the ALD process, the basic gas supply order of source gas supply/purge and reaction gas supply/purge is repeated until a desired thickness of a film is deposited. To realize excellent characteristics of the ALD process, there must be no inter-reaction between reaction gases during a process, differing from the conventional deposition method such as CVD, and to increase productivity for commercialization, switching time between the reaction gases must be swift. Showerhead-structured reactors have already been developed, but such structures have a limit in reducing the switching time between the reaction gases because of a problem such as a complex gas passage in the showerhead, and particles can be generated in the showerhead because of a reaction between remaining reaction gases therein, leading to low yield of semiconductor chips, so the above-noted structure has limits in commercialization.
To solve the problem of the atomic layer deposition device with the showerhead structure, a lateral flow reactor was developed. The lateral flow reactor has an optimized small reaction space for an atomic layer deposition process. The lateral flow reactor is well-described in the Korea Patent 624030 by ASM Genitech Korea Ltd. and U.S. Pat. No. 6,539,891, its family patent. The lateral flow reactor can have a gas flow control plate installed to supply at least two kinds of gases in the reaction space inside the reactor through a top part of the reactor.
The lateral flow atomic layer deposition device will now be described with reference to FIG. 1A and FIG. 1B.
FIG. 1A shows a cross-sectional view of a conventional lateral flow atomic layer deposition device, and FIG. 1B shows a gas flow control plate of a lateral flow atomic layer deposition device shown in FIG. 1A.
Referring to FIG. 1A, the atomic layer deposition device includes a substrate supporting plate 160 for supporting a substrate 150, a reactor cover 100 formed on the substrate supporting plate 160 and defining a reaction chamber while contacting the substrate supporting plate 160, a gas inlet 110 and a gas outlet 120 connected to the reactor cover 100 to supply gas to the reactor and exhaust gas from the reactor, respectively, a substrate supporting plate heater 170 for heating the substrate supporting plate 160, and a cover heater 130. A gas flow control plate 140 for controlling gas flow is provided in the reactor cover 100 to flow the gas in a lateral direction over the substrate and keep the gas flow close to a laminar flow in the reaction chamber. The reaction gas is supplied to the reactor through the gas inlet 110 on the top side of the reactor, it horizontally flows over the substrate 150, and it is then discharged to the outlet 120 on the top side of the reactor.
Referring to FIG. 1B, the gas flow control plate 140 includes gas inflow/outflow channels 141 and 142. The source gas and the reaction gas supplied through the gas inlet 110 pass through the gas inflow channel 141, spread fanwise to flow over the substrate 150, and gather while passing through the gas outflow channel 142, and it is then discharged through the outlet 120.
A gas flow distance in the center of the gas inlet channel 141 is greater than that on the edge thereof, and resultantly, the amount of gas supplied to the center of the substrate is less than that of gas supplied to the edge region of the substrate per unit time, leading to a thinner film thickness at the center of the substrate than at the edge of the substrate.
As described, the gases in the conventional lateral flow reactor are supplied to one side of the reaction space to flow in the lateral direction over the substrate, and are then discharged to the opposite side. However, in the above-described reactor, the gases flow to the edge of the substrate and a relatively smaller amount of gases are supplied to the center of the substrate to thus reduce the film thickness at the center of the substrate.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.